Statens Serum Institut (SSI) said it has detected five cases of Listeria, two of which can be related to the previous outbreaks of disease in 2013 and 2014 from deli meats.
SSI said the source of the infection remains unknown. It added five cases in one week were unusual with the norm being one.
Two other people are infected with two different Listeria types known from previous outbreaks.
The fifth person has a type of the pathogen not known from previous outbreaks. All five had underlying illness and two have died.
Site of previous outbreak investigatedfin
In the outbreak last year, the type of meat, known as ‘Rullepoelse’ was traced back to Jørn A. Rullepølser in Hedehusene, which was shut in August and products were withdrawn.
It has since re-opened as Schølers Pølser but it has been ruled out as a source of the current illnesses.
Dr Kåre Mølbak from SSI said the speed of recognizing the type of Listeria shows the monitoring system is getting better.
“2014 was the peak of the outbreak and we thought it was over. It is the same strain but it could be from a different source,” he told FoodQualityNews.
“We are concerned with the two cases which have the same strains of the outbreak last year, we would not like a repeat of what happened last year.
“With two cases it is difficult to find the source, with more cases it would be easier. Normally we would not start a big investigation with two cases but in this case it is the same strain that caused the outbreak so our threshold is lower.
“We will continue monitoring and interview the patients or family members for history of food intake to identify sources and give that information to the food authority who are investigating.”
Mølbak said whole genome sequencing (WGS) is now a routine tool for them.
The Danish Veterinary and Food Administration (DVFA) was told about the first three patients on the 22 April and the last two five days later.
A DVFA spokesman told us it is trying to find the source but it might be difficult if there are no new cases.
“We do not think that the new cases have been infected by meat products from the incriminated company in 2013/2014 as a comprehensive recall was carried out.
“At that time the outbreak strain was detected in some downstream businesses. At the moment we do not see new cases so we hope that they are isolated cases.
“We are in a very comprehensive investigation process and will continue our search until we either find the sources to the cases or have to stop if all traces [do not produce a result].”
When asked if it had investigated Jørn A. Rullepølser and distributors, the DVFA confirmed it had.
“We have done a thorough investigation of Schølers Pølser, the company formerly known as Jørn A,” it said.
“We have carried out audits and sampled both products and the environment at the production facilities and some distributors.
“All of these samples are negative, so we can rule out the possibility that Schølers has anything to do with the current cases.”
DVFA is in the process of taking samples from possible food companies and any Listeria bacteria found will be typed at the National Food Institute, Technical University of Denmark (DTU).
There are normally about 50 illness cases per year, but in 2009 and 2014 that total jumped to between 90 and 100. The mortality rate among the registered cases is about 25%.